Piston



Jul 31, 1928. 1,678,768

' L. R. DAVIS P I STON I Filed May 5, 1926 gmantez alibi/wag, v

Fatented July 31, 1928.

PATENT OFFICE;

LEWIS It. DAVIS, 01 SAN FBANG ISCQ GALH'ORNIA.

PISTON.

Application filed May 3, 1926. Serial No; 106,503.

The present invention relates to improvements in piston construction and has particular reference to pistons adapted for use in connection with internal combustion motors.

The object of the present invention as in my oo-pending application is the provision of means permittlng the employment of light weight material, such as aluminum, or its equivalent, in constructing the piston throughout. In the aforesaid co-pending application use is'made of a split skirt to compensate for the expansion which thepiston as a whole under oes from the action or .heat while in operatlon. With the present invention the aforesaid split skirt is 'replaced by a non-split or,continuous skirt,-

and certain structural details are employed for conducting the intense heat away from the piston proper to the skirt, the skirt in turn crating to transmit the heat to the wall 0 the cylinder whichby'reason of the presence of the surrounding water jacket operates to readil absorb the heat.

The above and other objects are accomplished by instrumentalities pointed out in the following specification. I

The invention is clearly defined in the claims.

A satisfactory embodiment of the invention is illustrated in the accompanying drawings forming part of "the specification and in which. l

Figure 1 is a vertical cross section of the invention.

Figure 2 is a view similar to Figure 1 and looking at right angles thereto.

Figure 3 is a cross sectional view on the line 3- 3 01? Figure 1 looking in the direction of the arrows, and

Figure 4 is a detail perspective of one of the abutment plates for the wrist pin.

The piston which is designated. generally by a is formed throughout of relatively light weight material such as aluminum or aluminum combined with other metal. The various parts, except for the wrist pin abutment plates, are integrally connected. The preferred, though by no means essential, method of forming the piston as shown is by die casting, it being understood that the I v outer surface is machined in the usual manner to provide for the necessary smoothness.

The feature of the present invention re- 1 sides in the, fact that the piston'as shown may be exteriorly dimensioned so as to propresent invention and its respective c linder,

there is no likelihood of oil enteringmto the combustlon space of the cylinder than in a case where'a cast iron piston is used. In adapting the piston of the present inventionto function as'just stated, Iform the same of an outer part or skirt 5 and an inner part comprising a skirt 6, a head 7 and one or more ribs 8 disposed between the outer.

and inner skirts 5 and 6 and cast integral 01:0tl16IYV1SQ formed therewith. The head 7 1s perlpherall provided with the usual grooves 9 for t e usual piston" rings, not

shown. 7 i.

The inner skirt 6 forms a downward conwith the bases of the grooves 9. The outer skirt 5 which surrounds the inner skirt 6 is dimensioned so that its periphery is in the plane of vthe peripher of head 7. This construction imparts to tile exterior of the so tinuation of the head 7 and is in alinement piston an appearance correspondin to the' exterior of the conventional type 0 piston.

the conventional distance. from the top of head .7 and the inner skirt 6 may extend downwardly to a point adjacent to the lower end of the outer skirt as shown or be shorter or longer, as desired.

In thickness the outer and inner skirts substantially correspond and their combined thickness is less than the depths of grooves 9. With this construction the space or clearness 10 is had between the skirts 5 and 6 as shown in the drawings. The space 10 is The outer skirt 5 extends downwardly for l bridged by one or more of the ribs 8. For purposes of illustration I have shown the ribs as extending longitudinally of space 10, their respective ends terminating at the upper end of the outer skirt 5 and the lower end of the inner skirt 6. The ribs are further arranged so that no two are disposed at diametrically opposite points. This arrangement, however, may be varied, if found desirable. The ribs as before stated are cast integral with the adjacent faces of the outer and inner skirts 5 and 6 and by their presence the outer skirt 5 is supported in the position shown. As shown in my copending application, the wrist pin bearing bosses 11 and 12 are cast with the inner skirt 6 and disposed interiorly thereof and in alinement with the openings 13 and 14 in the outer skirt 5 and throughwhich the wrist pin is inserted for connection to the piston rod.

As noted in Figure 1, plates 15 and 16 are arranged in the space 10 and extend over the outer ends of the openings of the bosses 11 and 12. One of these plates is shown in Figure 4 and the same is constructed of. flat thin sheet steel so that the plates may be readily flexed upon being introduced into the s ace 10. Small outwardly projecting lugs 1 are formed with the lower end of inner skirt 6'and operate to form bearings for the lower ends of plates 15 and 16 and prevent downward displacement thereof.

The presence of the plates prevents accidental endwise movement of the wrist pin through either side of the piston and possible scoring of the wall of the cylinder. Small openings 18 are provided in the upper portions of the plates and permit of manipulating the plates with a pointed tool in adjusting the plates within the space 10. When the plates are flexed as shown in Figure 3, they will be held against accidental movement by their own resiliency. However, additional means may be provided for preventing displacement of the plates in the form of lugs 19 cast integral with the'inner surface of the outer skirt 5.

When the motor is running,-the heat from head 7 is conducted downwardly by inner skirt 6 and is conducted away from the in ner skirt through theribs 8 by the outer skirt 5. In that the outer-skirt 5 is in contact with the relatively cool wall of the cylinder, the samereadily absorbs the heat from the'skirt 5. The portions of the outer skirt where connected to the ribs 8 may acquire a slightly higher temperature than the portions of the skirt between the ribs.

Any expansion due to such temperature,

however, will not operate to cause seizing of' the skirt with the cylinder wall, due to the Want of diametrical alinement between the ribs 8 when more-than one of these are used. In any event the difi'erence in temperatures between the aforesaid portions of the outer skirt can be only slight due to the conductive properties of the intervening portions of the skirt between the ribs and contact between these portions and relatively cool wall of the cylinder.

It will be noted that the spacing between the upper end of the outer skirt 5, and lowermost of the ribs 20 is such as to provide an additional ring groove. The presence of a ring in this groove forms a closure for the upper end of space 10 and checks lubricant from passing therethrough. The presence of the bosses 11 and 12, together with the plates 15 and 16 prevent lubricant from splashing outwardly and working upwardly into the combustion space of the cylinder by working around the rings. It is thus to be seen that the device of the present invention is ideally adapted to function as the ordinary cast iron piston and having the advantage over the latter type of piston by reason of its lightness and heat conductive properties.

Although I have shown and described one embodiment of my invention, it is to be un- 1. A piston comprising a head having an integral reduced. lower end portion constituting an inner skirt, an outer skirt conforming in cross-sectional area to the head and surrounding the inner skirt and disposed in spaced relation thereto, a rib disposed in the space betweenthe outer and inner skirts and rigidly secured thereto for su porting the outer skirt and operating to condhct heat from the inner to the outer skirt, the said inner skirt being interiorly provided with oppositely disposed open-ended wrist pin bearings and the outer skirt having wrist pin openings alining with said bearings, and plates disposed in the space between said outer and'inner skirts and arranged over they outer ends of said bearings.

2. A piston comprising a head and a portion reduced in cross sectional area with respect to the periphery of the head and extending downwardly therefrom and provided with means for supporting a wrist pin heat from the inner skirt to outer skirt separated from the former and small binding posts cast integral with both skirts holding the same in spaced relation throughout the lengths thereof.

4. A piston having two concentric skirts cylindrical throu bout the extent thereof and lengthwise we between the skirts holding the'same in spaced relation.

'5. A piston having a skirt with two opsing Wrist pin bosses between head and w h ttom of the skirt, a second skirt surrounding said first skirt andthin webs cast integral with both skirts and running lengthw1se with the skirts, thus creating an air gap the full length of the skirts. v

' LEWIS R. DAVIS. 

